Ed Chadwick grew up in Toronto and played junior for St. Michael's College before playing in the OHA with the Sault Ste. Marie Greyhounds. He began his professional hockey career at the age of 19, tending goal for the Pittsburgh Hornets for one game in 1952-52. After another two years in the minors with the Stratford Indians, Buffalo Bisons, and Winnipeg Warriors, Chadwick got his chance to play in the NHL when the Toronto Maple Leafs signed him to a contract.

Chadwick played in five games for the Leafs in 1955-56 as a replacement for Harry Lumley who was injured. He made the most of his opportunity, allowing just three goals while registering two shutouts. The game that stood out most vividly in his mind was the first game against the high-powered Montreal Canadiens. For the following two years, Chadwick was firmly installed as the team's number-one netminder, playing in 70 games in both seasons, the first year under head coach Howie Meeker. Billy Reay coached the team in 1957-58, before Punch Imlach took over the reigns in 1958-59, when Chadwick played in 31 games. In 1959-60, he played the majority of his games in the AHL with the Rochester Americans and was used on just four occasions with the Leafs in 1959-60.

After another two years in the minors, Chadwick played four games with the Boston Bruins in 1961-62. That was his last year playing in the NHL. He played professionally for another six years, before retiring as a member of the AHL's Buffalo Bisons after the 1967-68 season.

In retirement, Chadwick turned his focus to scouting, first with the Pittsburgh Penguins and the Oakland Seals before going to the New York Islanders for seven years in the same capacity. He was sent to the Islanders' farm team in Fort Worth and was told to make Glenn Resch a bonafide NHL goalie in two years. Chadwick had him ready in one. He then moved on to scouting positions in Buffalo and joined the Edmonton Oilers in 1981, where he remains to this day.

Recalled by Toronto from Winnipeg (WHL) to replace injured Harry Lumley in games from February 8 - 15, 1956. Traded to Boston by Toronto for Don Simmons, January 31, 1961. Traded to Detroit (Hershey-AHL) by Boston with Barry Ashbee for Bob Perreault, June, 1962. Traded to Chicago by Hershey (AHL) for cash, August, 1964.